Scaffold for an ion-conductive membrane

Abstract

A scaffold holding one or more ion-conductive ceramic membranes for use in an electrochemical cell is described. Generally, the scaffold includes a thermoplastic plate defining one or more orifices. Each orifice is typically defined by a first, second, and third aperture, wherein the second aperture is disposed between the first and third apertures. The diameter of the second aperture can be larger than the diameters of the first and third apertures. While at an operating temperature the diameter of the ceramic membrane is larger than the diameters of the first and third apertures, heating the scaffold to a sufficient temperature and for a sufficient time causes the third aperture's diameter to become larger than the membrane's diameter. Thus, heating the scaffold may allow the membrane to be inserted into the orifice. Cooling the scaffold can then cause the third aperture's diameter to shrink and trap the membrane within the orifice.

The invention claimed is: 
     
       1. A membrane scaffold comprising:
 a thermoplastic plate defining at least one orifice, wherein the orifice is defined by a first aperture having a first diameter, a second aperture having a second diameter, and a third aperture having a third diameter, wherein the second aperture is disposed between the first aperture and the third aperture, wherein the second diameter is larger than the first diameter and the third diameter; and 
 an ion-conductive ceramic membrane disposed within the second aperture of the orifice in a manner such that an outermost perimeter of the ceramic membrane is edge sealed with an inner surface of the second aperture, wherein, at an operating temperature, the ceramic membrane has a fourth diameter that is greater than the first diameter of the first aperture and the third diameter of the third aperture. 
 
     
     
       2. The membrane scaffold of  claim 1 , wherein the first diameter is smaller than the third diameter. 
     
     
       3. The membrane scaffold of  claim 1 , further comprising an O-ring that is compressed between the outermost perimeter of the ceramic membrane and the inner surface of the second aperture. 
     
     
       4. The membrane scaffold of  claim 1 , wherein the thermoplastic plate comprises a material that has a coefficient of thermal expansion such that heating the plate to a sufficient temperature and for a sufficient period of time causes the third diameter of the third aperture to expand to be larger than the fourth diameter of the ceramic membrane while the first diameter of the first aperture remains smaller than the fourth diameter of the ceramic membrane. 
     
     
       5. The membrane scaffold of  claim 1 , wherein the ceramic membrane comprises a ceramic material selected from a NaSICON-type material, a LiSICON-type material, and a KSICON-type material. 
     
     
       6. The membrane scaffold of  claim 1 , wherein the ceramic membrane comprises a NaSICON-type material. 
     
     
       7. The membrane scaffold of  claim 1 , wherein the ceramic membrane comprises a circular wafer. 
     
     
       8. The membrane scaffold of  claim 1 , wherein the scaffold comprises a plurality of ion-conductive ceramic membranes disposed within a plurality of orifices. 
     
     
       9. The membrane scaffold of  claim 1 , wherein at an operating temperature, the first diameter of the first aperture is between about 0% and about 15% smaller than the fourth diameter of the ceramic membrane. 
     
     
       10. The membrane scaffold of  claim 1 , wherein at an operating temperature, the second diameter of the second aperture is between about 0% and about 15% larger than the fourth diameter of the ceramic membrane. 
     
     
       11. The membrane scaffold of  claim 3 , wherein at an operating temperature, the second diameter of the second aperture is configured to compress a cross-sectional diameter of the O-ring between about 0% and about 70% of the O-ring's uncompressed state. 
     
     
       12. The membrane scaffold of  claim 1 , wherein at an operating temperature, the third diameter of the third aperture is between about 0% and 10% smaller than the fourth diameter of the ceramic membrane. 
     
     
       13. The membrane scaffold of  claim 1 , wherein when the scaffold is heated to an insertion point, the first diameter of the first aperture becomes between about 0% and about 10% smaller than the fourth diameter of the ceramic membrane. 
     
     
       14. The membrane scaffold of  claim 1 , wherein when the scaffold is heated to an insertion point, the second diameter of the second aperture becomes between about 0% and about 15% larger than the fourth diameter of the ceramic membrane. 
     
     
       15. The membrane scaffold of  claim 1 , wherein when the scaffold is heated to an insertion point, the third diameter of the third aperture becomes between about 0% and about 10% larger than the fourth diameter of the ceramic membrane. 
     
     
       16. A method for assembling a membrane scaffold, the method comprising:
 providing a thermoplastic plate defining at least one orifice, wherein the orifice is defined by a first aperture having a first diameter, a second aperture having a second diameter, and a third aperture having a third diameter, wherein the second aperture is disposed between the first aperture and the third aperture, wherein the second diameter is larger than the first diameter and the third diameter; 
 providing an ion-conductive ceramic membrane, wherein at an operating temperature the ceramic membrane has a fourth diameter that is greater than the first diameter of the first aperture and the third diameter of the third aperture; 
 heating the scaffold to a sufficient temperature above the operating temperature and for a sufficient period of time to cause the third diameter of the third aperture to become larger than the forth diameter of the ceramic membrane; 
 placing the ceramic membrane within the orifice; and 
 allowing the scaffold to cool so that an outermost perimeter of the ceramic membrane is edge sealed with an inner surface of the second orifice and the third diameter of the third aperture contracts to be smaller than the fourth width of the ceramic membrane. 
 
     
     
       17. The method of  claim 16 , wherein the first diameter is smaller than the third diameter. 
     
     
       18. The method of  claim 16 , further comprising placing an O-ring between the outermost perimeter of the ceramic membrane and the inner surface of the second aperture. 
     
     
       19. The method of  claim 16 , wherein the ceramic membrane comprises a NaSICON-type material. 
     
     
       20. The method of  claim 16 , wherein the first diameter of the first aperture remains smaller than the fourth diameter of the ceramic membrane during the heating of the scaffold. 
     
     
       21. The method of  claim 16 , wherein heating the scaffold involves heating the scaffold to a temperature above about 100 degrees Celsius and less than about 160 degrees Celsius. 
     
     
       22. The method of  claim 21 , wherein the heating the scaffold involves heating the scaffold for a period of time between about 1 and about 20 minutes. 
     
     
       23. The method of  claim 16 , wherein the scaffold comprises placing a plurality of ion-conductive ceramic membranes within a plurality of orifices. 
     
     
       24. The method of  claim 16 , wherein the heating the scaffold causes the third diameter of the third aperture to expand to be about 0.1% to about 6% larger than the third diameter of the third aperture at the operating temperature. 
     
     
       25. The method of  claim 16 , wherein at an operating temperature, the first diameter of the first aperture is between about 0% and about 15% smaller than the fourth diameter of the ceramic membrane. 
     
     
       26. The method of  claim 16 , wherein at an operating temperature, the second diameter of the second aperture is between about 0% and about 15% larger than the fourth diameter of the ceramic membrane. 
     
     
       27. The method of  claim 18 , wherein at an operating temperature, the second diameter of the second aperture is configured to compress a cross-sectional diameter of the O-ring between about 0% and about 70% of the O-ring's uncompressed state. 
     
     
       28. The method of  claim 16 , wherein at an operating temperature, the third diameter of the third aperture is between about 0% and 10% smaller than the fourth diameter of the ceramic membrane. 
     
     
       29. The method of  claim 16 , wherein when the scaffold is heated to an insertion point, the first diameter of the first aperture becomes between about 0% and about 10% smaller than the fourth diameter of the ceramic membrane. 
     
     
       30. The method of  claim 16 , wherein when the scaffold is heated to an insertion point, the second diameter of the second aperture becomes between about 0% and about 15% larger than the fourth diameter of the ceramic membrane. 
     
     
       31. The method of  claim 16 , wherein when the scaffold is heated to an insertion point, the third diameter of the third aperture becomes between about 0% and about 10% larger than the fourth diameter of the ceramic membrane. 
     
     
       32. An electrochemical cell comprising a membrane scaffold, the cell comprising:
 a first flow promoter comprising a cathode electrode; 
 a second flow promoter comprising an anode electrode; and 
 a membrane scaffold disposed between the first flow promoter and the second flow promoter, wherein the membrane scaffold comprises:
 a thermoplastic plate defining at least one orifice, wherein the orifice is defined by a first aperture having a first diameter, a second aperture having a second diameter, and a third aperture having a third diameter, wherein the second aperture is disposed between the first aperture and the third aperture, wherein the second diameter is larger than the first diameter and the third diameter, and wherein the first diameter is smaller than the third diameter; and 
 an ion-conductive ceramic membrane disposed within the second aperture of the orifice in a manner such that an outermost perimeter of the ceramic membrane is edge sealed with an inner surface of the second aperture, wherein, at an operating temperature, the ceramic membrane has a fourth diameter that is greater than the first diameter of the first aperture and the third diameter of the third aperture. 
 
 
     
     
       33. The electrochemical cell of  claim 17 , wherein the ceramic membrane comprises a NaSICON-type material. 
     
     
       34. The electrochemical cell of  claim 17 , wherein the membrane scaffold further comprises an O-ring that is compressed between the outermost perimeter of the ceramic membrane and the inner surface of the second aperture. 
     
     
       35. The electrochemical cell of  claim 17 , wherein the thermoplastic plate comprises a material that has a coefficient of thermal expansion such that heating the plate to a sufficient temperature and for a sufficient period of time causes the third diameter of the third aperture to expand to be larger than the fourth diameter of the ceramic membrane while the first diameter of the first aperture remains smaller than the fourth diameter of the ceramic membrane.